Controlling fracture growth

Abstract

The present invention provides methods of controlling the growth of one or more vertically oriented fractures in a subterranean formation during a fracturing treatment. A first fluid having a known density and containing a diverting agent is introduced into a formation to create a fracture. A second fluid which may contain proppant and having a known density different from the first fluid then is introduced into the fracture whereby the second fluid selectively overrides or underrides the first fluid. Such fluid control forces the first fluid to the bottom or top of the fracture whereby the diverting agent therein is caused to screen out and impede further downward or upward growth of the fracture. The introduction of the second fluid then can be continued to extend the fracture as desired.

What is claimed is: 
     
       1. A method of controlling the growth of one or more vertically oriented fractures in a subterranean formation during a fracturing treatment therein comprising: introducing a first fracturing fluid into said formation and into at least one fracture formed therein, said first fracturing fluid having a known density and containing a diverting agent;   introducing a second fracturing fluid into said fracture having a known density different from density of said first fracturing fluid whereby said second fracturing fluid selectably the overrides or underrides said first fracturing fluid and forces said first fracturing fluid to the bottom or top of said fracture whereby said diverting agent contained therein is caused to screen out along the bottom or top of said fracture and to thereby impede further downward or upward growth of said fracture; and   continuing the introduction of said second fracturing fluid into said fracture until said fracture is extended a desired amount.   
     
     
       2. The method of claim 1 wherein said first fracturing fluid is a high density fluid and said second fracturing fluid is a low density fluid whereby said second fracturing fluid overrides said first fracturing fluid. 
     
     
       3. The method of claim 1 wherein said first fracturing fluid is a low density fluid and said second fracturing fluid is a high density fluid whereby said second fracturing fluid underrides said first fracturing fluid. 
     
     
       4. The method of claim 1 which is further characterized to include the step of introducing a spacer fluid into said fracture after said first fracturing fluid and before said second fracturing fluid, said spacer fluid having a known density between the densities of said first and second fracturing fluids. 
     
     
       5. The method of claim 4 wherein said first and second fracturing fluids are more viscous than said spacer fluid. 
     
     
       6. The method of claim 5 wherein said diverting agent is selected from the group consisting of sand, silica flour, oil-soluble resins, and mixtures of such diverting agents. 
     
     
       7. A method of reducing the downward growth of one or more vertically oriented fractures in a subterranean formation during a fracturing treatment therein comprising: introducing a first fracturing fluid into said formation and into at least one fracture therein, said first fracturing fluid having a known density and containing a diverting agent;   introducing a second fracturing fluid into said fracture having a density lower than said first fracturing fluid whereby said second fracturing fluid overrides said first fracturing fluid, forces said first fracturing fluid to the bottom of said fracture and causes said diverting agent to be placed along the bottom of said fracture thereby impeding the further downward growth of said fracture; and   continuing the introduction of said second fracturing fluid into said fracture until said fracture is extended a desired amount.   
     
     
       8. The method of claim 7 which is further characterized to include the step of introducing a spacer fluid into said fracture after said first fracturing fluid and before said second fracturing fluid, said spacer fluid having a known density between the densities of said first and second fracturing fluids. 
     
     
       9. The method of claim 8 wherein said second fracturing fluid is more viscous than said spacer fluid. 
     
     
       10. The method of claim 9 wherein said diverting agent is selected from the group consisting of sand, silica flour, oil-soluble resins, and mixtures of such diverting agents. 
     
     
       11. A method of reducing the upward growth of one or more vertically oriented fractures in a subterranean formation during a fracturing treatment therein comprising: introducing a first fracturing fluid into said formation and into at least one fracture therein, said first fracturing fluid having a known density and containing a diverting agent;   introducing a second fracturing fluid into said fracture having a density higher than said first fracturing fluid whereby said second fracturing fluid underrides said first fracturing fluid, forces said first fracturing fluid to the top of said fracture and causes said diverting agent to be screened out along the top of said fracture thereby impeding the   further upward growth of said fracture; and continuing the introduction of said second fracturing fluid into said fracture until said fracture is extended a desired amount.   
     
     
       12. The method of claim 11 which is further characterized to include the step of introducing a spacer fluid into said fracture after said first fracturing fluid and before said second fracturing fluid, said spacer fluid having a known density between the densities of said first and second fracturing fluids. 
     
     
       13. The method of claim 12 wherein said first and second fracturing fluids are more viscous than said spacer fluid. 
     
     
       14. The method of claim 13 wherein said diverting agent is selected from the group consisting of sand, silica flour, oil-soluble resins, and mixtures of such diverting agents. 
     
     
       15. A method of controlling the growth of one or more vertically oriented fractures in a subterranean formation during a fracturing treatment therein comprising: introducing a first fracturing fluid into said formation and into at least one fracture formed therein, said first fracturing fluid containing a diverting agent and having a known density;   introducing a second fracturing fluid into said fracture, said second fracturing fluid containing a diverting agent and having a known density lower or higher than the density of said first fracturing fluid whereby said second fracturing fluid overrides or underrides said first fracturing fluid;   introducing a third fracturing fluid into said fracture, said third fracturing fluid having a known density between the densities of said first and second fracturing fluids whereby said third fracturing fluid is substantially confined between said first and second fracturing fluids and forces said first and second fracturing fluid to the bottom and top of said fracture whereby the diverting agent therein is caused to screen out and thereby impede the downward and upward growth of said fracture; and   continuing the introduction of said third fracturing fluid into said fracture until said fracture is extended outwardly a desired amount.   
     
     
       16. The method of claim 15 which is further characterized to include the step of introducing a first spacer fluid into said fracture after said first fracturing fluid and before said second fracturing fluid, said first spacer fluid having a known density between the densities of said first and second fracturing fluids. 
     
     
       17. The method of claim 16 which is further characterized to include the step of introducing a second spacer fluid into said fracture after said second fracturing fluid and before said third fracturing fluid, said second spacer fluid having a known density between the densities of said second and third fracturing fluids. 
     
     
       18. The method of claim 17 wherein said second fracturing fluid is more viscous than said first spacer fluid. 
     
     
       19. The method of claim 18 wherein said second and third fracturing fluids are more viscous than said second spacer fluid. 
     
     
       20. The method of claim 19 wherein said diverting agent is selected from the group consisting of sand, silica flour, oil-soluble resins, and mixtures of such diverting agents.